Electrical fuel injection system for internal combustion engines

ABSTRACT

An electrical fuel injection system for internal combustion engines, in which the operation of regular electromagnetic fuel injection valves is forcibly prevented so long as a starting electromagnetic fuel injection valve is in operation, whereby the engine can be started smoothly and positively without wetting the spark plug only with a readily atomizable fuel injected from the starting electromagnetic injection valve.

United States Patent 1191 Miyoshi et al.

1451 Nov. 12, 1974 1 ELECTRICAL FUEL INJECTION SYSTEM FOR INTERNALCOMBUSTION ENGINES [75] Inventors: Takeo Miyoshi, Toyota; Kazu Majima;Tetsuo Yamagata, both of Kariya; Susumu Harada, Okazaki; MotoharuSueishi, Kariya, all of Japan [73] Assignees: Nippondenso Co., Ltd.,Aichi-ken;

Toyota Jidosha Kogyo Kabushiki Kaisha, Toyota-shi, both of, Japan [22]Filed: Aug. 22, 1972 [21] Appl. No.: 282,663

[30] Foreign Application Priority Data Aug. 23. 1971 Japan 46-64293 [52]US. Cl 123/179 L, 123/32 EA, 123/179 G [51] Int. Cl... F02n 17/00, FO2b3/00 [58] Field of Search 123/32 CA, 32AE, 179 G,-

[56] References Cited UNITED STATES PATENTS Schmid 123/32 CA- 3.534.72310/1970 Tramontini 123/32 CA 3.614.945 10/1971 Schlagmuler 123/179 03,646,918 3 1972 Wagy 123/32 CA 3.680.532 8/1972 0111611. 123/179 03.704702 12/1972 AOIIO 123 32 CA 2 1973 Schmid 123 32 CA I FOREIGNPATENTS OR APPLICATIQNS 1,288,846 2/1969 Germany 123/1796 PrimaryExaminerChar1es J. Myhre Assistant Examiner-Ronald B. Cox Attorney,Agent, or FirmCushrnan, Darby &

- Cushman [57] ABSTRACT An electrical fuel injection system for internalcombustion engines, in which the operation of regular electromagneticfuel injection valves is forcibly prevented so long as a startingelectromagnetic fuel injec- 1 tion valve is in operation, whereby theengine can be started smoothly and positively without wetting the sparkplug only with a readily atomizable fuel injected from the startingelectromagnetic injection valve.

6 Claims, 3 Drawing Figures PATENIEDauv 12 I974 FIG. 3

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ENGINE ELECTRICAL FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINESBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates generally to a fuel injection system for internalcombustion engines and more particularly to an electrical fuel injectionsystem for a spark-ignition type internal combustion engine whichemploys no carburetor and in which the quantity of fuel required for theengine is electrically computed so that the electromagnetic injectionvalves are energized to inject fuel by pulse signals whose time widthcorresponds to the quantity of fuel required.

2. Description of the Prior Art In known systems of this type, inaddition to the regular electromagnetic injection valves designed toinject an electrically computed quantity of fuel during normal operationof the engine, a starting electromagnetic injection valve is provided toinject a readily atomizable fuel, i.e., a fuel which is easilyvaporized, to thereby ensure a good starting of the engine particularlyat low temperatures of the engine.

Also the known electrical fuel injection systems generally employ aso-called warming-up enrichment method by which the quantity of fuelinjected from the regular electromagnetic injection valves is increasedin accordance with the temperatures of an engine until the temperatureof the engine attains a predetermined value after'the starting thereof.

With the conventional electrical fuel injection systems of the typedescribed above, however, there is a drawback in that while both thestarting electromagnetic injection valve and regular electromagneticinjection valves inject the fuel upon starting the engine, un-

like the starting electromagnetic injection valve, the

regular electromagnetic injection valves place great importance on theirhigh-speed response characteristics and are adapted to limit the sprayangle of injected fuel so as to allow the injected fuel to be drawn intothe cylinders without falling along the inner walls of the intakemanifold. This fact has the effect of making the atomization of theinjected fuel poor. Consequently, if the driver cranks over and overagain owing to his lack of experience or the ignition spark is weakowing to the lowered voltage of the battery while the bad atomiza-SUMMARY OF THEINVENTION To overcome the foregoing difficulties, it is anobject ofthe present invention to provide an electrical fuel injectionsystem for. internal combustion engines in which, noting the fact thatat the operating temperatures of the starting electromagnetic. injectionvalve, a large quantity of poorly atomizable fuel injected from theregular electromagnetic injection valves only tends to wet the sparkplug and thus gives rise to an inconvenience instead of contributing toa smooth starting of like to electrically compute from these inputs thequanvide an electrical fuel injection system for internal combustionengines of the type in which the quantity of fuel required for aninternal combustion engine is electrically calculated and the regularelectromagnetic injection valves are energized to inject fuel by meansof pulse signals whose time width corresponds to the said fuelquantityrequired and there is provided a starting electromagnetic injectionvalve designed to inject an engine starting fuel when starting theengine independent of the regular electromagnetic injectionvalves, thesystem comprising a start detector for detecting the start of theinternal combustion engine to produce an output signal, and a circuitfor receiving the output signal of the start detector to prevent theoperation of the regular electromagnetic injection valves and to ener-'gize only the starting electromagnetic injection valve.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an electrical circuit diagramshowing a first I embodiment of the electrical fuel injection system foran internal combustion engine according to the present invention.

FIG. 2 is an electrical circuit diagram showing an embodiment of thetemperature detector and the start detector employed in the electroniccomputing'circuit of the system of the present invention.

FIG. 3 is an electrical circuit diagram showing a second embodiment-ofthe system according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1illustrating a first embodiment of the present invention, numeral 1designates an internal combustion engine with four cylinders; 2 an airintake manifold; 3 an air cleaner; 4 a throttle valve. Nu merals 5, 6, 7and 8 designate regular electromagnetic injection valves adapted, whenenergized, to open and inject fuel and located opposite to and adjacentthe air inlet valves in the respective cylinders. Numeral 9 des-.ignates a starting electromagnetic injection valve'located at aposition more remote from the intake manifold 2 than the regularelectromagnetic injection valves 5 to 8 and directed toward the intakemanifold 2. Numeral l0 designates an electronic computing circuit forelectrically detecting the number of revolutions of the engine 1, thepressure in the intake manifold 2 and'the tity of fuel required for theengine and thus produce successively at its output terminals 10a, 10b,10c and 10d pulse signals whose time width corresponds to the computedfuel requirement of the engine. The-electronic computing circuit 10 alsoincludes therein a temperature detector for detectingthe temperature ofthe engine and a start detector for detecting the starting of theengine, whereby when the temperature of the engine detected at the'startthereof is below a preset value of 20C, for example, a signal isproduced at the output terminal 10 e. Numerals 11, 12, 13 and 14designate NAND gates having one input thereof respectively connccted tothe output terminals 10a, 10b, 10c and 10d of the electronic computingcircuit 10. Numerals 15, 16, 17 and 18 designate inverter amplifierswherein the outputs of the NAND gates 11, 12, 13 and 14 are inverted andamplified for application to the magnetic coils of the regularelectromagnetic injection valves 5,

6, 7 and 8. Numeral 19 designates a non-inverter amplifier wherein thesignal produced at the output terminal 106 of the electronic computingcircuit 10 is amplified and then applied to the magnetic coil of thestarting electromagneticinjection valve 9; 20 an inverter for invertingthe signal produced at the output terminal 100 and then applying theinverted signal to the other input terminals of the NAND gates 11, 12, 13 and 14.

The temperature detector and the start detector in the electroniccomputing circuit 10 are constructed as shown in FIG. 2, in whichnumeral 21 designates the temperature detector; 22 a thermistor immersedin the cooling water of the engine 1; 23, 24 and 25, resistors; 26 anamplifier; 27 a comparator amplifier; and 28 a Zener diode forgenerating a reference voltage which determines a preset temperature. Itis prearranged such that a signal is generated at the output terminal ofthe comparator amplifier 27 when the voltage representing mistor 22 islower than the reference voltage generated by the Zener diode 28 andrepresenting the preset temperature, while a 1 signal is generated atsaid output terminal when the former voltage is higher than the latterreference voltage. Numeral 29 designates a starting motor for crankingthe engine 1; 30 a starter switch which is closed to operate thestarting motor 29 for starting the engine 1; 31'the start detector;32-and 33, resistors; 34 a transistor. It is prearranged such that whenthe starter switch 30 is open, that is, whenthe engine 1 is not beingstarted, the transistor34 is .nonconducted producing a 1 signal at itscollector, whereas when they starter switch 30 is closed, that is, whenthe engine 1 is being started, the transistor 34 is conducted producinga 0 signal at its collector. Numerals 35'and 36 designate diodes; 37 and38, resistors; 39 a transisz tor whose collector constitutes the outputterminal c;

40 a battery installed in the vehicle.

1 parator amplifier 27 of the temperature detector 21, so

that the transistor 39 is rendered non-conductive producing a 1 signalat its collector, i.e.,'the output terminal lOe of the electroniccomputing circuit 10. This 1 signal is amplified by the non-inverteramplifier 19 and his then applied to the magnetic coil of the startingelectromagnetic injection valve 9 to inject the fuel into the intakemanifold 2. On the other hand, the 1 signal produced: at the outputterminal 102 is inverted by the inverter and the inverted 0 signal isthen applied to the input terminals of the NAND gates 11., 12, 13 and14.This closes the NAND gates 11 to 14 and thus prevents the signalsproduced at the output terminals 100,

I 101;, 10c and 10d of the electronic computing circuit l0 from passingthrough the NAND gates 11 to 14. Consequently, if the temperatureof theengine 1, when starting is below the preset value, the operation of theregular electromagnetic injection valves 5, 6, 7 and 8 is forciblyprevented so that only the starting electromagnetic injection valve 9 isoperated to inject therefrom a readily vaporable fuel thereby ensuring asmooth starting of the engine. As the engine 1 thus started eventuallystarts rotating by its own effort so that the cranking by the startingmotor 29 is no longer required, the starter switch 30 is opened and thusthe transistor 34 of the start detector 31 is rendered non-conductiveproducing a 1 signal at the collector thereof. When this occurs,independently of the output signal of the temperature detector 21, thetransistor-39 is rendered conductive thusproducing an 0 signal at theoutput terminal 10c of the electronic computing circuit 10. Theoccurrence of this 0 signal results in the de-energization ofthestarting electromagnetic injection valve 9 stopping the injection ofthe fuel therefrom, and simultaneously the 0 signal produced at theoutput terminal 10e is inverted by the inverter 20 so that the inverted1 signal is applied to the NAND gates 11, 12, 13 and 14 causing them toopen. After the engine has started positively in this manner, the pulsesignals produced at the output terminals 10a, 10b, 10c and 10d of theelectronic computing circuit 10 for normal operation of the engine areapplied in a predetermined sequence to the magnetic coils of the regularelectromagnetic injection valves 5, 6, 7 and 8 through the NAND gates11, 12, 13 and 14 and through the inverter amplifier 15, 16, 17 and 18where the pulse signals are inverted and amplified. This causes theregular electromagnetic injection valves 5, 6, 7 and 8 to inject thefuel as required by the engine 1. At this time, as with the conventionalsystems, the regular electromagnetic injection valves 5, 6, 7 and 8inject, if required, an additional amount of fuel so as to warm up theengine until the temperature of the engine 1 attains another presetvalue of C, for example, which is different from the one determined bythe temperature detector 21. In this case,'such an enrichment forwarming up does not give rise to any inconvenience, since the engine hasalready started.

On the other hand, if the temperature of the engine a 1, when starting,is higher than the preset value established by the temperature detector2 1,a 0 signal is produced at the output terminal We of the electroniccomputing circuit 10 so that the starting electromagnetic injectionvalve 9 does not operate and instead the regular electromagneticinjection valves 5, 6, 7 and 8 come into operation. In other words,since the engine 1 has already warmed up, with no fuel injected from thestarting electromagnetic injection valve 9, the engine 1 can be smoothlystarted without wetting the spark plug by means of the fuel injectedfrom'the regular electromagnetic injection valves 5, 6, 7 and 8.

While, in the first embodiment described above, the operation of theregular electromagnetic injection valves 5, 6, 7 and 8 is prevented andthe starting electromagnetic injection valve 9 alone is operated only incase the temperature of the engine 1, when starting, is below thepresent value, in practice,'whenever the engine 1 is to be started, theoperation of the regular electromagnetic injection valves 5 to 8 may beforcibly prevented to allow the starting electromagnetic injectionvalve9 to operate alone independently of the tempera-- ture of the engine 1.One form of the arrangement for this purpose will be explained withreference to FIG. 3 illustrating a second embodiment of the presentinvention. In H6. 3, reference numerals identical with those which areused in FIGS. 1 and 2 designate the identical parts or theirequivalents, and the collector of the transistor 34 of the startdetector 31, i.e., the output terminal is connected to one input of theNAND gates 11, 12, 13 and 14 and the output terminal 10a is alsoconnected to the starting electromagnetic injection valve 9 through aninverter amplifier 41.

The operation of this embodiment is as follows: as the starter switch 30is closed so that the starting motor 29 is operated to start the engine1, the transistor 34 of the start detector 31 is rendered conductiveproducing at its collector a 0 signal which is applied to and closes theNAND gates 11, 12, 13 and 14. When this occurs, the operation of theregular electromagnetic injection valves 5, 6, 7 is forcibly preventedallowing the starting electromagnetic injection valve 9 to operate aloneso as to inject a readily atomizable fuel. After the engine 1 hasstarted, the starter-switch 30 is opened so that the transistor 34 ofthe start detector 31 is rendered nonconductive producing a 1 signal atits collector. This 1 signal is applied to stop the operation of thestarting electromagnetic injection valve 9 and simultaneously the NANDgates 11, 12, 13 and 14 are opened. Thereafter, the pulse signalsgenerated at the output terminals 10a, 10b, 10c and 10d of theelectronic computing circuit 10 energize the regular electromagneticinjection valves 5, 6, 7 and 8 to inject the fuel to meet the fuelrequirement of the engine 1. It should be noted that the presentinvention is not limited to the embodiments described hereinabove andthat various modifications and embodiments can be devised that will fallwithin the spirit and scope of the present invention. For example, theNAND gates 11, 12, 13 and 14 and the inverter may be incorporated in theelectronic computing circuit 10 and moreover these circuit elements maybe converted into configurations using negative logic.

lt will thus be seenthat the present invention has a remarkable effectin that since the operation of the regular electromagnetic injectionvalves 5, 6, 7 and 8 is forcibly prevented while the startingelectromagnetic injection valve 9 is in operation, if the temperature ofthe engine 1 is low and thus the atomization of the fuel injected fromthe regular electromagnetic injection valves 5, 6, 7 and 8 is poor, theengine 1 may be smoothly started without wetting the spark plug by meansof a readily atomizable fuel injected from the starting electromagneticinjection valve 9. There is another remarkable effect in that if theengine 1 has warmed up to the extent that the fuel injected from theregular electromagnetic injection valves 5, 6, 7 and 8 can be vaporizedsatisfactorily, the engine can be readily and positively started onlywith the fuel injected from the regular electromagnetic injection valves5, 6, 7 and 8 without operating the starting electromagnetic injectionvalve 9.

We claim:

1. In an electrical fuel injection system for internal combustionengines wherein the fuel requirement of an engine is electricallycomputed by an electronic computing circuit sothat the regularelectromagnetic injection valves are energized to inject the fuel bypulse 'signals the time width of which corresponds to the fuelrequirement, and wherein a starting electromagnetic injection valve isprovided to atomize and inject, independently and exclusively of theregular electromagnetic injection valves, an engine starting fuel whenstarting the engine, the combination comprising a start detector fordetecting the start of the engine and for generating an output signal,and a circuit means connected with said start detector for receivingsaid output signal of said start detector for preventing the operationof the regular electromagnetic injection valves and for energizing onlythe starting electromagnetic injection valve to thereby provide anatomized fuel to said netic injection valves, an engine starting fuelwhen starting the engine, the combination comprising a start detectorfor detecting the start of the engine and for generating an outputsignal when said engine is being started, a temperature detector fordetecting the temperature of the engine, said detector generating anoutput signal when the engine. temperature is lower than a preset value,and a circuit means connected with said start detector and saidtemperature .detector for preventing the operationof the'regularelectromagnetic injection valves and for energizing only the startingelectromagnetic injection valve when said output signals of said startdetector and said temperature detector.are simultaneously generated.

3. An electrical fuel i'njectionsystem according to claim 1, whereinsaid circuitcomprises:

a logic gate circuit having a first input terminal connected to saidelectronic computing circuit, a second input terminal connected to saidstart detector, and a first output terminal 'connectedto said regularelectromagnetic injection valves; and

an inverter circuit having an input terminal connected to said startdetector, and an output terminal connected to said startingelectromagnetic injection valve.

4. The electrical fuel injection system of claim 1 8 wherein saidcircuit comprises gating means coupling the output of said electroniccomputing circuit with said regular electromagnetic injection valve,

means response to the output of said start detector for inhibiting saidgating means when said internal combustion engine is being started" andfor enabling said gating means after said internal combustion engine'isstarted, and

gating means responsive to the output signal of sai I start detector forenergizing'the starting electromagnetic valve. 5. The electrical fuelinjection'system of claim 2 wherein said circuit comprises: j

a logic gating circuit having a first input terminal connected'to saidelectronic computing circuit, an inverter having an input terminalconnected to said start detector and an output'terminal connected to theother input terminals of said logic gating circuit, said logic gatingcircuit having an.

output terminal connected to said regular electromagnetic injectionvalve wherein said logic gating circuits are inhibited when the outputsignals of said start detector and said temperature detector aresimultaneously generated and wherein said to the output of said startdetector and said temperature detector for inhibiting said gating meanswhen said internal combustion engine is being started andthe temperatureof said engine is below a preset level, and for enabling said gatingmeans after said engine is started or the temperature of said enginegoes above said preset level, and means responsive to the output signalof said start detector and said temperature detector for energizing thestarting electromagnetic valve when said engine is being started andwhen the temperature is below a preset level.

1. In an electrical fuel injection system for internal combustionengines wherein the fuel requirement of an engine is electricallycomputed by an electronic computing circuit so that the regularelectromagnetic injection valves are energized to inject the fuel bypulse signals the time width of which corresponds to the fuelrequirement, and wherein a starting electromagnetic injection valve isprovided to atomize and inject, independently and exclusively of theregular electromagnetic injection valves, an engine starting fuel whenstarting the engine, the combination comprising a start detector fordetecting the start of the engine and for generating an output signal,and a circuit means connected with said start detector for receivingsaid output signal of said start detector for preventing the operationof the regular electromagnetic injection valves and for energizing onlythe starting electromagnetic injection valve to thereby provide anatomized fuel to said engine when said engine is starting.
 2. In anelectrical fuel injection system for internal combustion engines whereinthe fuel requirement of an engine is electrically computed by anelectronic computing circuit so that the regular electromagneticinjection valves are energized to inject the fuel by pulse signals thetime width of which corresponds to the fuel requirement, and whereIn astarting electromagnetic injection valve is provided to atomize andinject, independently and exclusively of the regular electromagneticinjection valves, an engine starting fuel when starting the engine, thecombination comprising a start detector for detecting the start of theengine and for generating an output signal when said engine is beingstarted, a temperature detector for detecting the temperature of theengine, said detector generating an output signal when the enginetemperature is lower than a preset value, and a circuit means connectedwith said start detector and said temperature detector for preventingthe operation of the regular electromagnetic injection valves and forenergizing only the starting electromagnetic injection valve when saidoutput signals of said start detector and said temperature detector aresimultaneously generated.
 3. An electrical fuel injection systemaccording to claim 1, wherein said circuit comprises: a logic gatecircuit having a first input terminal connected to said electroniccomputing circuit, a second input terminal connected to said startdetector, and a first output terminal connected to said regularelectromagnetic injection valves; and an inverter circuit having aninput terminal connected to said start detector, and an output terminalconnected to said starting electromagnetic injection valve.
 4. Theelectrical fuel injection system of claim 1 wherein said circuitcomprises: gating means coupling the output of said electronic computingcircuit with said regular electromagnetic injection valve, meansresponse to the output of said start detector for inhibiting said gatingmeans when said internal combustion engine is being started and forenabling said gating means after said internal combustion engine isstarted, and gating means responsive to the output signal of said startdetector for energizing the starting electromagnetic valve.
 5. Theelectrical fuel injection system of claim 2 wherein said circuitcomprises: a logic gating circuit having a first input terminalconnected to said electronic computing circuit, an inverter having aninput terminal connected to said start detector and an output terminalconnected to the other input terminals of said logic gating circuit,said logic gating circuit having an output terminal connected to saidregular electromagnetic injection valve wherein said logic gatingcircuits are inhibited when the output signals of said start detectorand said temperature detector are simultaneously generated and whereinsaid logic gating circuits are enabled when said engine is started orsaid engine temperature goes above a preset level.
 6. The electricalfuel injection system of claim 2 wherein said circuit comprises gatingmeans coupling the output of said electronic computing circuit with saidregular electromagnetic valve, means responsive to the output of saidstart detector and said temperature detector for inhibiting said gatingmeans when said internal combustion engine is being started and thetemperature of said engine is below a preset level, and for enablingsaid gating means after said engine is started or the temperature ofsaid engine goes above said preset level, and means responsive to theoutput signal of said start detector and said temperature detector forenergizing the starting electromagnetic valve when said engine is beingstarted and when the temperature is below a preset level.